1,200-Ton Boulder Moved Inland by Ancient Tonga Tsunami

The Maka Lahi boulder, a massive limestone monolith weighing around 1,200 tons and located over 650 feet inland on Tonga's main island Tongatapu, provides compelling evidence of an ancient megatsunami that struck the region approximately 7,000 years ago. Discovered by University of Queensland researcher Martin Köhler, this boulder was dislodged from a coastal cliff over 30 meters above sea level and transported inland by a colossal wave estimated to be around 150 feet high, generated by a landslide-triggered tsunami. Numerical and wave-flume modeling ruled out storms or cyclones as causes, indicating the exceptional force required to move such a massive rock, which is heavier than three fully-loaded Boeing 747s. This tsunami was likely triggered by seismic activity near the Tonga-Kermadec Trench, and the event is the earliest known Holocene tsunami in the Pacific, far exceeding previously recorded tsunami heights in the region. The discovery enhances understanding of tsunami dynamics and supports improved coastal hazard assessments for tsunami-prone areas globally. Local oral traditions may still preserve memories of such catastrophic events, underscoring the profound impact of these ancient tsunamis on both landscapes and cultures.